Field of the invention
[0001] The present invention relates to variable electrical generators for converting mechanical
rotational and/or displacement energy to electrical energy, for example to a generator
which is operable to vary dynamically its electrical output as well as coping with
dynamically changing mechanical input rotation and/or reciprocating speeds. Moreover,
the present invention also relates to methods of operating these variable electrical
generators. Furthermore, the present invention concerns methods of constructing these
variable electrical generators. Additionally, the present invention relates to software
products executable on computing hardware for implementing methods of the present
invention.
Background of the invention
[0002] On account of depletion of fossil fuel reserves, as well as concerns of climate change
resulting from anthropogenic activities, attention has been focused in recent years
on renewable energy systems. Conventional approaches the electricity generation often
involve of form of reservoir, for example a hydroelectric facility includes a water
dam providing a steady stream of water which can be regulated via a water valve to
drive a turbine, and a hot nuclear reactor core is capable of storing considerable
thermal energy for providing a steady stream of steam under high pressure which can
be regulated via a steam valve to drive a turbine. In contradistinction, many renewable
energy systems driven by wind, tidal flows and ocean wave motion experience a wide
range of motion amplitudes, motion velocities, motion frequencies and/or motion directions.
Moreover, extreme weather conditions often result in a large dynamic range of motion
at various times throughout a year. In consequence, energy pickoff from these renewable
energy systems is often technically difficult to implement. A conventional approach
to cope with these problems of energy pickoff is to employ hydraulic apparatus, for
example hydraulic piston-cylinder pump apparatus as described in United States patent
US 6 476 511 B1 (Yemm et al.), or hydraulic pump apparatus as described in international
PCT patent application WO 2007/016120A2. However, hydraulic systems are prone to wear, and are relatively energy inefficient
on account of viscous drag occurring in hydraulic fluids employed therein.
[0003] As an alternative to employing hydraulic power pickoff, it is feasible to employ
a variable speed generator. Several types of variable speed generators are known,
but they are often very rough devices which are not really ideal for applications
such as wind power or tidal energy production. Large wind turbines for electricity
generation rotate with a fairly low rotation rate (rpm) and current generators designed
for use with these turbines utilize either:
- (i) a staged gear system between a wind turbine rotor and a generator, wherein rotational
speed is controlled by adjusting wind turbine blade pitch; or
- (ii) a large diameter generator directly coupled to a wind turbine rotor, wherein
the generator is designed to operate at low rotation rates.
The output power from the generator is conventionally rectified and then phase formed
via power electronics operating at high switching frequencies, for example at frequencies
of several kHz. These approaches (i) and (ii) are relatively expensive to implement,
especially in respect of electronic apparatus required to rectify and phase form the
generated electrical power provided by the generator.
[0004] Document
US2619087 A presents a traditional fixed rpm generator which produces a sinus curve directly
proportionate to the rotational speed. All the coils produce 3 phases that are locked
and work in unison in relation to the fixed variable magnetic field.
[0005] Similarly, a generator shown in document
DE102007054719 A1 also produces only sine curves.
Summary of the invention
[0006] The present invention seeks to provide a variable electrical generator which is better
adapted for coping with variable mechanical input speeds and various input rotation
directions and/or linear movement directions.
The present invention seeks to provide an advanced form of variable electrical generator
which is more suited to mass production whilst also providing large power generating
performance and robust operation.
[0007] According to a first aspect of the present invention, there is provided a variable
electrical generator as claimed in appended claim 1: there is provided a variable
electrical generator for converting mechanical motion to electrical power, wherein
the generator includes at least a stator element and a rotor element including coils
and magnets, characterized in that the generator includes a configuration of modules
including the coils for generating wavelets (30) in response to the coils interacting
magnetically with the magnets, and a control arrangement for combining the wavelets
for generating a composite synthesized power output from the generator.
[0008] The invention is of advantage in that the output can be rapidly dynamically adjusted
by controlling a manner in which the wavelets are combined together to synthesize
the output.
[0009] Optionally, in the generator, the modules are spatially collocated with their corresponding
coils to provide power signal metamorphosis at an early stage within the generatorr.
This collocation potentially avoids a need for expensive and complex high-frequency
electronic switching units later which are conventionally employed to condition outputs
from conventional generators to a form suitable to feed onto an electricity distribution
grid. Optionally, the variable electrical generator is beneficially implemented so
that the modules are operable to generate wavelets whose duration (
d) is shorter than a duration of cycle (
D) of an alternating waveform of the output from the generator. Conveniently, when
constructing the generator, the stator includes coils and is arranged to remain substantially
stationary in operation, and the rotor includes magnets and is arranged to rotate
and/or reciprocate in operation relative to the stator to induce wavelet signals in
the coils. Optionally, the variable electrical generator is implemented so that the
modules are electrically coupled together in a two-dimension switching matrix including
at least one series path for adding potentials and at least one parallel path for
current preading for generating the output. Optionally, the variable electrical generator
is implemented so that the modules are operable to switch between a non-conductive
state, a shorted state, a negative wavelet state and a positive wavelet state when
in operation in response to control signals provided from the control arrangement.
Optionally, the control arrangement is distributed between a control unit external
to the modules and microcontrollers present in the modules. Optionally, when implementing
the variable electrical generator, the modules are coupled in communication with the
control arrangement via an optical data highway. More optionally, when implementing
the variable electrical generator, the optical data highway is operable to direct
data selectively between the control arrangement and the modules by way of wavelength
division multiplexing (WDM). More optionally, the variable electrical generator is
implemented so that the modules are operable to communicate diagnostic signals regarding
their operating status to the control arrangement, and to receive control signals
from the control arrangement concerning timing information and/or polarity information
in respect of their respective wavelets.
[0010] Optionally, the variable electrical generator is implemented so that the modules
are arranged to be unplugged and plugged into their respective positions on the stator
and/or rotor, for example for maintenance and/or repair purposes.
[0011] Optionally, the variable electrical generator is implemented so that the modules
include solid state switching devices for switching at least half-cycles of induced
electrical signals induced within the coils in operation for generating wavelets.
[0012] Optionally, the variable electrical generator is implemented so that the control
arrangement includes an input for use as a reference when synchronizing and/or adjusting
an amplitude and/or phase of the output during operation.
[0013] According to a second aspect of the invention, there is provided a module for use
in a variable electrical generator pursuant of the first aspect of the invention,
wherein the module includes a microcontroller for providing local control of the module,
a coil coupled to a switching arrangement for generating wavelets under control of
the microcontroller, and an optical communication interface for receiving control
data for controlling the module and/or for communicating diagnostic information from
the module.
[0014] According to a third aspect of the invention, there is provided a method of using
a variable electrical generator for converting mechanical motion to electrical power,
wherein the generator includes at least a stator element and a rotor element including
coils and magnets, characterized in that the method includes:
- (a) generating wavelets in a configuration of modules including the coils for generating
wavelets in response to the coils interacting magnetically with the magnets; and
- (b) using a control arrangement to combine the wavelets for generating a composite
synthesized power output from the generator.
[0015] According to a fourth aspect of the invention, there is provided a renewable energy
system for converting linear and/or rotating motion of mechanical apparatus into electrical
energy, wherein the apparatus is operable to cause relative movement between a rotor
and a stator of a variable generator pursuant to the first aspect of the invention
for generating a power output from the system. Optionally, operation of the system
is determined by diagnostic data generated by the variable generator. Optionally,
the renewable energy system is implemented so that the mechanical apparatus includes
at least one of: a tidal water turbine, a wind turbine, an oscillating wind vane,
an ocean float, a hydroelectric turbine, a steam turbine.
[0016] According to a fifth aspect of the invention, there is provided a method of maintaining
a variable generator, the generator being pursuant to the first aspect of the invention,
the method including steps of:
- (a) determining operating status of modules of the generator;
- (b) unplugging and replacing one or more defective modules as identified in step (a).
[0017] According to a sixth aspect of the invention, there is provided a method of providing
responsive load stabilization to an electrical distribution grid by using a variable
electrical generator pursuant to the first aspect of the invention, the generator
being coupled to the grid, characterized in that the method includes:
- (a) sensing one or more parameters indicative of a degree of electrical loading being
experienced by the grid;
- (b) adjusting wavelet selection in the generator to absorb or inject electrical power
into the grid so as to assist to stabilize the grid against deviations in voltage
and/or frequency of said grid resulting from said degree of electrical loading.
It will be appreciated that features of the invention are susceptible to being combined
in various combinations.
Description of the diagrams
[0018] Embodiments of the present invention will now be described, by way of example only,
with reference to the following diagrams wherein:
- FIG. 1
- is an illustration of an embodiment of a variable electrical generator pursuant to
the present invention, and a representation of synthesis of an output waveform by
combining wavelets in various combinations;
- FIG. 2A
- is an illustration of an embodiment of a variable electrical generator pursuant to
the present invention, wherein the generator is implemented in a wide-diameter form;
- FIG. 2B
- is an illustration of an embodiment of a variable electrical generator pursuant to
the present invention, wherein the generator is implemented in a long narrow-diameter
form;
- FIG. 2C
- is an illustration of an embodiment of a variable electrical generator pursuant to
the present invention, wherein the generator is implemented to include a central stationary
stator with associated modules, and a rotatable rotor circumferentially surrounding
the stator;
- FIG. 3
- is a further illustration of output waveform synthesis by using wavelets which are
in phase and in quadrature phase for achieving an improved quality of synthesis, thereby
reducing a need for output filtering to remove harmonic content present in the output
from the generator;
- FIG. 4
- is an illustration of a central stator of an embodiment of a variable electrical generator
pursuant to the present invention;
- FIG. 5
- is an illustration of a spiral disposition of modules along a stator of an embodiment
of a variable generator pursuant to the present invention;
- FIG. 6A
- is an illustration of a ring-type rotor element of a rotor of an embodiment of a generator
pursuant to the present invention;
- FIG. 6B
- is an illustration of a set of ring-type rotor elements arranged in a phase-offset
manner, the rotor elements forming a part of a rotor of an embodiment of a generator
pursuant to the present invention;
- FIG. 7
- is a schematic illustration of a module of a stator suitable for constructing a generator
pursuant to the present invention;
- FIG. 8A
- is a schematic illustration of an embodiment of an electrical power circuit for use
in modules of the invention;
- FIG. 8B
- is a schematic illustration of a matrix electrical connection arrangement of modules
of the invention;
- FIG. 9
- is a schematic diagram of an offshore wind turbine system, namely a wind "farm", including
a plurality of wind turbines equipped with variable generators pursuant to the present
invention; and
- FIG. 10
- is a schematic diagram of an embodiment of a generator pursuant to the present invention
for converting linear motion, for example reciprocating linear motion, to electrical
energy in a variable manner.
[0019] In the accompanying diagrams, an underlined number is employed to represent an item
over which the underlined number is positioned or an item to which the underlined
number is adjacent. A non-underlined number relates to an item identified by a line
linking the non-underlined number to the item. When a number is non-underlined and
accompanied by an associated arrow, the non-underlined number is used to identify
a general item at which the arrow is pointing.
Description of embodiments of the invention
[0020] The present invention is based upon a concept which is illustrated in FIG. 1, namely
that an alternating power output
10 provided from an electrical generator
20 is susceptible to being synthesized by selectively switching a large number of smaller
wavelets
30 which have a magnitude
p and a duration
d which are considerably smaller and shorter respectively than a magnitude
M and a duration
D of the alternating power output
10 provided from the generator
20. If required, a filter
40, for example implemented by a combination of inductors and capacitors, may be employed
to filter high-order harmonic signal components present in the output
10 from the generator
20. A benefit of this approach is that the wavelets
30 are capable of being switched rapidly in response to dynamically changing input rotation
directions or rotation speeds of a rotor
50 of the generator
20. Moreover, mass-produced solid state electronic modules
80 can be employed which are dedicated to switching their respective wavelets
30. Moreover, the modules
80 are beneficially implemented to be individually controllable, for example via a general
optical data bus from a control unit
70 operable to direct operation of the generator
10. Such a manner of operation is beneficial because failure of a few of the modules
80 does not disable operation of the generator
10 in general, but merely results in potentially a more coarsely synthesized output
10. Furthermore, the modules
80 can be mounted in a stacked arrangement along the rotor
50 and/or stator
60 for ensuring a more uniform and manageable potential gradient occurs in operation,
thereby reducing any risk of electrical breakdown or flash-over. The aforementioned
wavelets
30 are generated by employing relatively small magnetic poles and associated magnets
90 disposed around the rotor
50 and its associated stator
60 for generating the wavelets
30 at various different angular positions of the rotor
50 relative to the stator
60. Electrically insulating cooling fluid, for example synthetic silicone oil or forced
air, is circulated through the modules
80 to remove heat generated therein when in operation. Optionally, the rotor
50 and the stator
60 have fitted thereto an angular sensor, for example an optical encoder, for providing
the control unit
70 with an indication of the rotation angle of the rotor
50 relative to the stator
60. In operation, the generator in FIG. 1 optionally receives an external synchronization
signal S, and is operable to couple wavelets generated by the modules
80 at appropriate times to generate the output
10 synchronized to the signal S. However, it will be appreciated that the wavelets can
be switched in such a manner that the generator of FIG. 1 is also capable of generating
a direct current (DC) output
10 as well as an alternating current (AC) output
10.
[0021] The generator
20 is capable of being employed in a direct drive manner, for example where it is directly
coupled to, or even integral with, a turbine. Alternatively, the generator
20 may be coupled via a gearbox, for example a fixed-ratio gearbox, to a turbine. Thus,
the generator
20, also referred to as a variable voltage generator "WG", is capable of operating as
a direct-drive apparatus. The generator
20 may be specifically designed for direct-drive applications where input speed and
torque to the generator
20 variesconsiderable, for example in response to changing tidal or wind conditions.
Example applications for the generator
20 can be on-shore or off-shore wind turbines or underwater tidal turbines. Moreover,
the generator
20 is also susceptible to being employed in free-cylinder reciprocating combustion machines
devoid of a crankshaft structure. The generator
20 of FIG. 1 will now be described in greater detail.
[0022] On account of its modular form of construction and operation, the generator
20 is intrinsically capable of providing several additional benefits. For example, the
generator
20 is capable of adapting its operation between:
- (a) a stand-alone mode of operation; and
- (b) a coordinated mode of operation which allows the generator 20 to function in conjuncture with other units,
thereby enabling highly robust systems to be constructed which are tolerant to multiple
component failures within the generator
20. Such a degree of robustness renders the generator
20 ideal for renewable energy applications, for example in offshore wind turbine applications
where high reliability is important on account of access for maintenance purposes
being restricted, for example during stormy winter conditions. In operation, the generator
20 is capable of generating output at any desired frequency, overall waveform shape,
voltage magnitude and phase relative to a reference signal; the generator
20 can even generate direct current (DC), thereby avoiding a need for rectification
components external to the generator
20.
[0023] Although the wavelets
30 are illustrated in FIG. 1 as being in phase and of mutually of similar size, it will
be appreciated that the generator
20 may be constructed so that the wavelets
30 have mutually different polarities, mutually different relative phases and mutually
different magnitudes. Beneficially, the magnets
90 and their associated modules
80 are disposed in a spiral manner as illustrated in FIG. 1 to obtain various relative
phases for the wavelets
30 to enable the control unit
70 to finely control the output
10, for example for synchronizing the output
10 to an electrical power distribution grid. The wavelets
30 can, for example, be implemented as a binary series of magnitude in a manner akin
to a binary sequence 1, 2, 4, 8 ... to enable the magnitude and form of the output
10 to be finely adjusted.
[0024] The generator
20 can be constructed to utilize a wide diameter configuration, for example in a pancake-type
arrangement as illustrated in FIG. 2A. In order to be regarded as a "wide diameter"
generator, the diameter of the rotor
50, similarly the stator
60, should be in an order of at least 1.5 times greater than its axial active length.
Alternatively, the generator
20 can be implemented in a long but small diameter configuration as illustrated in FIG.
2B. In order to be regarded to be a "long rotor" generator, the rotor
50 is beneficially in an order of at least 1.5 times longer than its diameter, with
the stator
60 implemented along a length of the rotor
60. In FIG. 2C, the generator
20 is implemented such that rotor
50 encloses the stator
60, wherein the stator
60 is stationary in operation and central to the generator
20. The modules
80 are each beneficially implemented as an integrated subunit with one or more associated
pickup coils. Moreover, the modules
80 are beneficially arranged in several rows or spirals in respect of a rotating axis
of the generator
20. The number of magnets
90 and coils of the modules
80 determines a generating power output capability of the generator
20. Moreover, the waveform output resolution of the generator
20 is beneficially adapted in each case to an intended range of operating speeds expected
for the generator
20.
[0025] Conventional variable generator designs are operable to rectify power signals generated
by generator pickup coils to generate a rectified output which is then phase-formed
using power electronic components to produce a final output power signal having a
desired frequency, phase and voltage magnitude. Such power electronic components are
expensive, inflexible and cause much localized energy loss, namely "hotspots", which
can result in a single point of critical failure. The power electronic components
are usually implemented as high-frequency switching devices, for example power field-effect-transistors
(FETS), thyristors, Darlington transistors and similar, capable of chopping the rectified
signal, for example in a pulse-width-modulated (PWM) manner, to synthesize an output
power signal which is amplitude, frequency and phase adjusted.
[0026] In contradistinction, generators implemented pursuant to the present invention perform
in quite a different manner in comparison to aforementioned conventional generator
designs. Thus, conventional variable generators perform two separate operations of
rectification of alternating coil signals to direct current state (DC), and then subsequent
waveform generation using electronic devices to generate a synthesized output signal
as conventional employed. Generators 20 ("WS") pursuant to the present invention included
a plurality of modules
80 for generating wavelets
30 which are then selectively combined by binary switching to synthesize an output power
waveform. This approach pursuant to the present invention provides the following benefits:
- (a) wavelet 30 switching can occur at a much lower frequency which reduces switching losses and
thereby improves efficiency, and also enables lower-performance silicon switching
devices to be utilized;
- (b) loss of supply of one wavelet 30 does not cause catastrophic failure of the generator 20; in an event that one or more of the modules 80 become defective such that their wavelets 30 are not available for output waveform synthesis, the control unit 70 is operable to select amongst other available wavelets 30 to provide a next-best possible synthesis of the output 10.
An adaptive control system of the control unit
70 steers power flow within the generator
20 so that outputs of the individual coils
80 are re-arranged in cooperation with all the other coils
80 in real time to produce the desired output
10, irrespective of the input frequency as determined by a rotation rate of the rotor
50. Since control electronic components of each module
80 only deal with their own associated pickup coil
80, for example each pickup coil
80 having a maximum power in a range of 5 kW to 10 kW, considerable amounts of power
within the generator
20 can be controlled and modulated with simple mass-produced off-the-shelf electronic
switching components. Thus, generators
20 pursuant to the preset invention eliminate conventional rectification and phase forming
stages of conventional generator systems, thereby providing cost savings, more efficient
operation and more reliable operation.
[0027] In FIG. 3, there is shown a combination of wavelets
30 to synthesize sinusoidal output waveforms for the output
10, namely by employing wavelets
30 which are mutually in quadrature phase. An approximate half sinusoidal signal
110 is thus generated as illustrated at the top region of FIG. 3 by combining one in-phase
wavelet
30A with two quadrature wavelets
30B and three in-phase wavelets, wherein the wavelets are of similar polarity. It is
feasible to synthesize a half sinusoidal signal of longer relative duration by combining
more wavelets
30D, 30E, 30F, 30G as illustrated at a bottom region of FIG. 3. By combining these individual wavelets,
almost any range of frequencies, voltages and currents can b provided at the output
10, namely independently of the input frequency determined by rotation rate of the rotor
50, without the need to rectify or phase-form signals generated by the coils.
[0028] In FIG.4, a practical implementation for the stator
60 is shown, wherein the rotor
50 (not shown in FIG. 4) is disposed in a peripheral manner as illustrated in FIG. 2C;
the stator
60 is thus beneficially stationary in operation, thereby rendering cable coupling to
the stator
60 possible without a need to use slip-rings. It will be appreciated that the generator
20 experiences considerable mechanical stresses when designed to generate in an order
of MegaWatts (MW) of electrical power such that the magnets
90 and the modules
80 need to be mechanically robust and properly mechanically supported, for example to
withstand centrifugal forces. For example, the magnets
90 are beneficially fabricated from Neodynium materials and supported in a compliant
polymer or rubber mount of the rotor
50 to spread forces to avoid snapping or fracture of the permanent magnets
90 in operation; for example, polyurethane bedding of the magnets
90 is optionally employed. The modules
80 are robustly mechanically supported as well as being provided with cooling. Furthermore,
the modules
80 are beneficially stacked together in a manner to ensure a gradual potential gradient
occurs in operation therealong; such potential distribution is especially important
when the generator
20 is to provide the output
10 at a magnitude in an order of kilovolts (kV) to avoid any tendency to flash-over.
The modules
80 are beneficially mounted onto an insulating central tube
150 through which forced air cooling or cooling liquid is circulated in operation; for
example, electrically-insulating and substantially optically-transparent silicone
oil is beneficially employed as a liquid coolant. The modules
80 are beneficially mounted onto axial vanes
160 projecting from the central tube
150, wherein the vanes
160 are in thermal communication with the central tube
150. Magnetic pole pieces
170, for example fabricated from laminate silicon steel, of the modules
80 are beneficially mounted in respect of the vanes which are both robust, able to resist
stress, and yet offer a degree of flexibility to cope with mechanical shocks which
could otherwise damage the generator
20. The modules
80 are beneficially mutually similar to enable the stator
60 to be fabricated from mass-produced items for reducing its cost. Moreover, when the
generator
20 requires servicing, any defective modules
80 can be readily diagnosed and them subsequently unplugged from the vanes
160 and/or the central tube
150 and substituted with corresponding new functional modules
80. Beneficially, the modules
80 are provided with a shared optical communication highway, for example implemented
in a manner akin to Ethernet, for enabling control signals to be sent from the control
unit
70 to the modules
80 for controlling switching of the modules
80, and for conveying feedback signals from the modules
80 back to the control unit
70 indicative of operation of the modules
80. If required, optical wavelength division multiplexing (WDM) can be employed for different
categories of control and feedback signals exchanged between the modules
80 and the control unit
70. Moreover, optical radiation conveyed via the optical highway can be used to provide
power for control electronic components included in each of the modules
80, for example using power-generating photocells included in the modules, there providing
electrical isolation. Use of optical radiation is of especial benefit because:
- (a) it is relatively immune to electrical interference;
- (b) it provides for relatively high communication data rates to and from the modules;
and
- (c) it provides an intrinsic approach to electrical isolation between modules 80 which would not be possible in an alternative configuration wherein electrical control
signals were employed.
Optionally, the modules
80 are disposed in a slightly spiral manner onto the stator
60 as illustrated in FIG. 5 for enabling improved waveform synthesis to be achieved
in operation with greater phase resolution by way of providing a range of wavelets
30 with mutually slightly differing phase characteristics.
[0029] When a configuration for the generator
20 is employed as illustrated in FIG. 1, the rotor
50 is beneficially fabricated from a series of ring elements as indicated by 300 in
FIG. 6A. Each ring element
200 includes permanent magnets
210, for example Neodynium ceramic permanent magnets, disposed around a ring-like support
220 which can be rigidly mounted to a supporting shaft in operation. The magnets
210 are implemented in a radial vane-like manner with air gaps therebetween as illustrated.
Moreover, vane-like projections from the support
220 assist to support the magnets
210 mechanically which are subject to major stress when the generator
20 is in operation providing large quantities of output power, for example in an order
of several hundred kW's, or even several MW's.
[0030] Several of the ring elements
220 can be mounted axially together with an angular displacement therebetween as illustrated
in FIG. 6B for providing the control unit
70 with a greater choice of wavelets
30 which can be combined to generate the output
10. Thus, the rotor
50 is susceptible to being constructed from a multiple of ring elements
220 which are robustly assembled together. In an event that one or more of the elements
220 become damaged, for example their magnets
90 become fractured, they can be simply replaced in their entirety during routine maintenance
of the generator
20. The ring elements
220 are beneficially constructed from one or more of: metal, carbon fiber, composite
materials, plastics polymer materials, ceramic materials. The rotor
50 and the stator
60 are mounted together within a housing with an appropriate arrangement of bearings
so that the rotor
50 is operable to rotate relative to the stator
60 to generate electrical power at the output
10. Mechanical and/or magnetic bearings and/or fluid bearings can be employed, depending
upon application for the generator
20 and its designed power generating capacity.
[0031] The modules
80 will now be described in greater detail with reference to FIG. 7. Each module
80 is a self-contained wavelet
30 generator which can be mounted in a stacked configuration against other similar modules
80, or mounted onto supports of a supporting structure of the stator
60 as aforementioned. The module
80 is provided with a cooling arrangement
300, for example based upon circulated insulating silicone cooling oil and/or forced air
cooling. Moreover, the module
80 also includes a releasable mounting arrangement
310 for enabling the module
80 to be adequately mechanically supported when exposed to various mechanical stresses
when in operation; the mounting arrangement
310 beneficially includes screws, registration pins, rubber bushes and so forth. The
module
80 includes a coil
320 for interacting with magnetic flux generated by magnets
90 of the rotor
50. An output of the coil
320 is coupled to a rectifier arrangement
330 and then via a switching network
340 to the wavelet output
30; the switching network
340 is designed to operate at relatively low switching frequencies corresponds to the
duration d of the wavelets
30. Such operation is very different to conventional high-frequency pulse-width-modulated
(PWM) electronic power conditioning circuits which are costly and energy inefficient
due to high-frequency switching losses occurring at high frequencies in an order of
kHz. Moreover, the module
80 also includes a bidirectional optical interface
360 for receiving control instruction from the control unit
70 and for output diagnostic data and/or confirmatory data to the control unit
70. The interface
360 is able to provide for rapid data rates as well as providing electrical isolation
between modules
80 in a most robust and cost-effective manner. A microcontroller
350 controls operation of the module
80 at a local level; in practice, control of the generator
20 is beneficially executed in a distributed manner between the control unit
70 and the microcontrollers
350 of the modules
80. Moreover, the interface
360 is conveniently implemented using high-speed photodetectors and data-modulated solid-state
laser devices. As aforementioned, the interface
360 is designed to receive and transmit at various different optical carrier radiation
wavelengths, for example in a manner of wavelength division multiplexing (WDM), to
enable a single general optical data highway to be used within the generator
20 to control operation of all the modules
80 of the generator
20. Optionally, a plurality of optical data highways can be employed in the generator
20, for example for emergency backup purposes in an event that a main optical data highway
of the generator
20 becomes obscured for any reason. Each coil
320 and its associated electronic components are constructed as a stand alone mass-produced
unit that can easily be replaced, for example even while in operation. The ability
to construct the generator
20 as a large-diameter arrangement, or as a long small-diameter arrangement, also lends
itself to integration into a wide range of conventional and exotic turbine designs
without requiring its basic component parts to be re-designed. As aforementioned,
all configurations of the generator
20 can have monopole or dipole magnetic setups with internal or external rotating magnets,
for example as depicted in FIG. 2A, FIG. 2B and FIG. 2C.
[0032] Referring next to FIG. 8A, there is shown a representation of electronic switching
components employed to implement the module
80. The module
80 can be implemented using a variety of electronic switching components, for example
field effect transistors (FET), bipolar transistors (BJT), triacs, silicon controlled
rectifiers (SCR), Darlington transistors, silicon carbide transistors, silicon germanium
transistors, and so forth. Most preferable, on account of low cost and robustness,
the module
80 is implemented using silicon controlled rectifiers SCR1 to SCR8 as illustrated. Silicon
controlled rectifiers SCR are purchasable to have up to 2 kV blocking voltage performance,
a current conducting performance of several thousand amperes and be packaged in flat
ceramic capsules which are easily mechanically incorporated into the module
80. The silicon controlled rectifiers SCR include gate terminals which are triggered
from the microcontroller
350 of the module
80; triggering of the silicon controlled rectifiers SCR is beneficially achieved via
optical triggering and/or or via isolation ferrite pulse transformers. In operation,
a silicon controlled rectifier SCR only conducts when triggered at its gate terminal.
Moreover, conduction through a silicon controlled rectifier SCR ceases when a potential
thereacross is smaller than a threshold magnitude or the silicon controlled rectifier
SCR becomes reversed biased across its main two terminals. The module
80 in FIG. 8A has four conducting modes, namely:
- (a) a first mode, wherein the module 80 provides effectively a short-circuit path between its terminals T1, T2;
- (b) a second mode, wherein there is an open circuit between the terminals T1, T2;
- (c) a third mode, wherein a negative wavelet 30 half-cycle is directed from the coil 320 to the terminals T1, T2; and
- (d) a fourth mode, wherein a positive wavelet 30 half-cycle is directed from the coil 320 to the terminals T1, T2.
Beneficially, the module
80 includes a first safety fuse FS1 for isolating the entire module
80 in a situation of gross failure, and a second safety fuse FS2 for protecting the
coil
320 in a situation of gross failure. The silicon controlled rectifiers SCR1 to SCR8 are
arranged in a bridge-type configuration as illustrated in FIG. 8A. In the first mode,
the silicon controlled rectifiers SCR3, SCR4, SCR7 and SCR8 are triggered into a conducting
state, whereas the silicon controlled rectifiers SCR1, SCR2, SCR5 and SCR6 are in
a non-conducting state. In the second mode, none of the silicon controlled rectifiers
SCR1 to SCR8 are in a conducting state, namely they are all in an open-circuit state.
In the third mode, the silicon controlled rectifiers SCR2 and SCR7 are in a conducting
state, and the silicon controlled rectifiers SCR1, SCR3 to SCR6, and SCR8 are in a
non-conducting state. In the fourth mode, the silicon controlled rectifiers SCR1 and
SCR8 are in a conducting state, and the silicon controlled rectifiers SCR2 to SCR7
are in a non-conducting state.
[0033] As illustrated in FIG. 8B, the modules
80 are beneficially coupled electrically together in a two-dimensional matrix including
m x
n modules
80. Certain of the modules
80 are optionally omitted from the matrix. By such an arrangement, current load can
be shared between modules
80 coupled in parallel, and large potentials can be provided at the output
10 by the modules
80 being coupled in series. For example, if required, the output
10 can be many kV's in magnitude which potentially circumvents a need to interface the
generator
20 via transformers to an electrical distribution grid, thereby saving installation
cost and reducing energy losses. Optionally, the matrix includes several hundred modules
80 for synthesizing the output
10 as a sinusoidal signal with relatively little harmonic content, for example less
than 1% harmonic content. As aforementioned, the modules
80 of the matrix optionally provide mutually different wavelet
30 amplitudes for enabling even more accurately synthesized waveforms to be synthesized
for the output
10. However, it will be appreciated that the matrix can also be controlled to provide
direct current DC output which can be fed directly to long-distance submerged ocean
cables for reducing long-distance power transmission losses.
[0034] The variable generator
20 ("WG") provides many intrinsic benefits in comparison to conventional approaches
to generator construction. Conceptually, the variable generator
20, for example adapted for use in an offshore wind turbine for electrical power generation,
can be considered to be a spatial collocation of small power plants that can be dynamically
rearranged to combine their power outputs in various combinations to absorb energy
from an electrical power network or supply energy to the electrical power network;
such absorption or supply can be achieved by adjusting phase of the output
10 relative to phase of an electrical grid to which the generator
20 is coupled, namely by selecting time instances when the wavelets
30 are selectively added together to generate the output
10. Alternatively, or additionally, power absorption or power supply can also be controlled
by modulating a magnitude of the output
10, namely by how many wavelets
30 that the control unit
70 elects to combine to synthesize its output waveform at the output
10. Situations where power absorption is desirable arise when an electrical grid is momentarily
overloaded and power needs to be extracted from the grid to be stored in rotational
inertia of the rotor of the wind turbine. A situation when power supply to the electrical
grid is required is when numerous consumers are extracting power from the electrical
power network. The generator
20, when used in an offshore wind turbine, is thus capable of providing electrical power
output as well as very rapid electrical grid network demand response stabilization
with a response time potentially within one mains electricity cycle. Such demand response
stabilization is vastly more prompt than any pump storage systems which are conventionally
used for electrical power grid stabilization; an example of a pump storage demand
response stabilization facility is Dinorwig in Wales, United Kingdom. The generator
20 is thus highly suitable for use with smart grids (in USA, "supergrid").
[0035] In principle, various measured parameters can be used by the microcontrollers
350 and/or the control unit
70 to control the generator
20, or even a configuration of several generators
20 operating together in a coordinated manner. An example of a measured parameter is
temperature within a given module
80, or number of hours a given generator
20 has been operating within a wind farm (for example, for uniformly distributing wear-and-tear
amongst generators
20 to enhance overall operating reliability between servicing operations).
[0036] For example, referring to FIG. 9, a system
500 comprises several offshore wind turbines
510 equipped with variable generators
20 pursuant to the present invention. The system
500 is beneficially operated according to a method wherein a control centre
520 of the system
500 decides, by way of an independent decision, to start the wind turbines
510 in a western region
530 of the system
500, namely a wind "farm", first if the wind blows from a westerly direction; in other
words, the system
500 activates those wind turbines
510 which are capable of generating energy most efficiently first. Beneficially, the
control units
70 of the generators
20 employed within the system
500 are operable to maintain a temporal log of accumulative output power from the generators
20, for example for spreading wear-and-tear within the system
500 and/or for determining maintenance schedules for the system
500.
[0037] In another method of operation, the control centre
520 seeks to set in operation first a wind turbine
510 that has hitherto produced least output, for example in order to spread wear-and-tear
and/or to prevent seldom-used mechanisms seizing up in corrosive offshore environments.
The control centre
520 is optionally an automatic arrangement controlling the system
500 without a need for human intervention. Optionally, the control centre
520 is adaptive and refines its operating routines for the wind turbines
510 based upon feedback from monitoring the outputs
10 and from receiving information from maintenance activities.
[0038] Beneficially, control logic employed for the system
500 is based on a self-organizing neural control; this type of neural control means that
the system
500 itself will at any given time decide an optimum operating scenario of a single generator
20 or a combination of generators
20 based on predetermined values set by an operator of the system
500. Any value desired by the operator can be integrated in a control algorithm employed
for a single unit or the entire system
500. An example could be to operate the system
500 in such a way that it maximizes output but minimizes maintenance, and additionally
minimizes temperature in the individual components of the electronic subunits, and
so forth. Other measures could, for instance, be to optimize power output of a generator
20 of the system
500, or the entire system
500, but allow optimized power to be overridden by responsive load demands exhibited by
an electrical power grid coupled to the system
500. Beneficially, automatic system compensation is adopted by the system
500 in an event that one or more of the generators
20 or their associated wind turbines
510 fail, experience seasonal variations, and so forth.
[0039] Methods of making decision are beneficially based on criteria which are decided and
weighted by an operator of the system
500; these methods allow the system
500 to prioritize independently in real time based on whatever system operating effects
are desired. The system
500 could, for example, be instructed to maintain absolute voltage and frequency control
at its point of delivery at any given time, or even compensate/counteract noise on
the electric power grid if this is desired. The generators
20 are beneficially susceptible to being adapted to smart unit and smart grid scenarios.
[0040] If an individual wind turbine
510 experiences a gust of wind that could potentially create a short unwanted power boost
onto an electrical distribution grid coupled to the turbine
510, the generator
20 of the wind turbine
510 is beneficially operable to counteract an electrical power surge resulting from the
boost by enabling a rotor of the wind turbine
510 to accelerate so that energy of the gust is converted to rotational kinetic energy
of the rotor. This operating characteristic is capable of enabling a more stable electrical
supply grid to be achieved. In a coordinated scenario, in an event that a base load
in the grid suddenly drops by 100 MW, for example everyone unplugs their electric
automobiles to drive to work, a wind turbine farm employing generators
20 and producing 100 MW at the time could instantaneously switch and in reality produce
momentarily 100 MW of additional power by decelerating rotors of the wind turbines
510. Such an approach reduces a need for short-term load shedding to be implemented within
the electrical distribution grid. The system
500 beneficially continually adjusts itself and failure in any individual component or
unit therein will have a negligible effect on the overall performance of the system
500. If a component fails in the system
500, the only negative effect would be a power loss equal to the failed component. This
is a very useful feature, especially if the production unit is placed in a remote
area, offshore or underwater and the next planned maintenance interval is a long time
off. Not only can the generator
20 adapt in real time to noise or unbalanced loads, but it can also act as an instantaneous
load shedder equal at any given time to the instantaneous power produced by the system
500 either in an individual production unit or distributed across a number of independent
production units.
[0041] The generator
20 is optionally susceptible to being modified to function as a component part of a
linear generator for converting reciprocating linear motion resulting from combustion
processes to electrical energy, for example as a component part of an apparatus as
described in granted European patent
EP0772735B1. In renewable energy systems, reciprocating linear motion also arises as a consequence
of floats bobbing up and down on ocean waves, and in oscillating-vane wind energy
devices; such motion is also beneficially converted to electrical energy using the
generator
20. In FIG. 10, the stator
60 is shown disposed in a linear planar matrix, optionally a skewed or irregular matrix,
for interfacing to a linear reciprocating "rotor"
50 equipped with a plurality of magnets
90.
[0042] Although inclusion of the magnets
90 in the rotor
50 and coils
320 in the stator
60 are described in the foregoing, it will be appreciated that each of the stator
60 and rotor
50 optionally include both magnets
90 and coils
320 in a hybrid type of arrangement. Optionally, slip rings and/or magnetic inductive
couplings can be used for transferring generated power.
[0043] Although use of the generator
20 in renewable energy systems is described most in the foregoing, it will be appreciated
that the generator
20 can be adapted for use in more convention installations, for example:
- (a) in hydroelectric facilities;
- (b) in conjunction with steam turbines of coal, nuclear, gas, solar and geothermal
power stations.
[0044] Modifications to embodiments of the invention described in the foregoing are possible
without departing from the scope of the invention as defined by the accompanying claims.
Numerals included within parentheses in the accompanying claims are intended to assist
understanding of the claims and should not be construed in any way to limit subject
matter claimed by these claims.
1. Variabler Stromgenerator (20) zum Umwandeln mechanischer Bewegung in elektrische Energie,
wobei der Generator (20) wenigstens ein Statorelement (60) und ein Spulen (320) und
Magnete (90) umfassendes Rotorelement (50) aufweist,
dadurch gekennzeichnet, dass
der Generator (20) eine Konfiguration von Modulen (80), welche die Spulen (320) zum
Erzeugen von Wavelets (30) als Reaktion auf ein magnetisches Interagieren der Spulen
(320) mit den Magneten (90) umfasst, wobei die Module (80) zum Erzeugen von Wavelets
(30) während einer Dauer (d) betreibbar sind, die kürzer als eine Periodendauer (D)
einer im Betrieb an den Ausgang (30) bereitgestellten wechselnden Wellenform ist,
und eine Steueranordnung (70) zum selektiven Kombinieren der Wavelets (30) umfasst,
um einen zusammengesetzten synthetischen Leistungsausgang (10) von dem Generator (20)
zu erzeugen.
2. Variabler Stromgenerator (20) nach Anspruch 1, wobei die Module (80) räumlich mit
ihren entsprechenden Spulen (320) nebeneinander angeordnet sind.
3. Variabler Stromgenerator (20) nach Anspruch 1, wobei der Stator (60) Spulen (320)
umfasst und dazu angeordnet ist, um im Wesentlichen stationär in Betrieb zu bleiben,
und der Rotor (50) Magnete (90) umfasst und dazu angeordnet ist, im Betrieb relativ
zu dem Stator (60) zu rotieren und/oder zu pendeln.
4. Variabler Stromgenerator (20) nach Anspruch 1, wobei die Module (80) elektrisch zusammen
in einer zweidimensionalen Schaltermatrix gekoppelt sind, die wenigstens einen Serienpfad
zum Hinzufügen von Potentialen der Wavelets (30) und wenigstens einen parallelen Pfad
zum Stromverteilen zwischen Wavelets (30) umfasst, um den Ausgang (10) zu erzeugen.
5. Variabler Stromgenerator (20) nach Anspruch 1, wobei die Module (80) zum Schalten
zwischen einem nicht-leitenden Zustand, einem kurzgeschlossenen Zustand, einem negativen
Wavelet-Zustand und einem positiven Wavelet-Zustand betreibbar sind, wenn diese als
Reaktion auf von der Steueranordnung (70, 80) bereitgestellte Steuersignale in Betrieb
sind.
6. Variabler Stromgenerator (20) nach Anspruch 1, wobei die Module (80) in Kommunikation
mit der Steueranordnung (70, 80) über eine optische Datenautobahn gekoppelt sind,
die zum selektiven Weiterleiten von Daten zwischen der Steueranordnung (70) und den
Modulen (70) durch Wellenlängen-Multiplexen betreibbar ist, und wobei die Module (80)
zum Kommunizieren von diagnostischen Signalen betreffend deren Betriebsstatus zu der
Steueranordnung (70) und zum Empfangen von Steuersignalen von der Steueranordnung
(70) betreffend Zeitvorgabeinformationen und/oder Polaritätsinformationen hinsichtlich
deren jeweiliger Wavelets (30) betreibbar sind.
7. Variabler Stromgenerator (20) nach Anspruch 1, wobei die Module (80) dazu angeordnet
sind, ausgesteckt und in ihre jeweiligen Positionen auf dem Stator (60) und/oder Rotor
(50) eingesteckt zu werden.
8. Variabler Stromgenerator (20) nach Anspruch 1, wobei die Module (20) Festkörperschaltvorrichtungen
(330, 340) zum Schalten von wenigstens halben Zyklen induzierter elektrischer Signale
umfassen, die innerhalb der Spulen (320) im Betrieb induziert werden.
9. Variabler Stromgenerator (20) nach Anspruch 1, wobei die Steueranordnung (70) einen
Eingang zum Verwenden als eine Referenz umfasst, wenn eine Amplitude und/oder Phase
des Ausgangs (10) während dem Betrieb synchronisiert und/oder angepasst wird.
10. Modul (80) zum Verwenden in einem variablen Generator (20) nach einem der vorangegangenen
Ansprüche, wobei das Modul (80) einen Mikrokontroller (350) zum Bereitstellen einer
lokalen Steuerung der Module (80), eine Spule (320), die zu einer Schaltanordnung
(330, 340) zum Erzeugen von Wavelets (30) unter der Kontrolle des Mikrokontrollers
(350), und eine optische Kommunikationsschnittstelle (260) zum Empfangen von Steuerdaten
zum Steuern der Module (80) und/oder zum Kommunizieren diagnostischer Informationen
von den Modulen (80) umfasst.
11. Verfahren zum Verwenden eines variablen Stromgenerator (20) zum Umwandeln mechanischer
Bewegung zu elektrischer Energie, wobei der Generator (20) wenigstens ein Statorelement
(60) und ein Spulen (320) und Magnete (90) umfassendes Rotorelement (50) aufweist,
dadurch gekennzeichnet, dass das Verfahren umfasst:
(a) Erzeugen von Wavelets (30), deren Länge (d) kürzer als eine Periodendauer (D)
einer im Betrieb an den Ausgang (30) bereitgestellten wechselnden Wellenform ist,
in einer Konfiguration von Modulen (80), die die Spulen (320) zum Erzeugen von Wavelets
(30) als Reaktion darauf erzeugen, dass die Spulen (320) magnetisch mit den Magneten
(90) interagieren; und
(b) Verwenden einer Steueranordnung (70) zum selektiven Kombinieren der Wavelets (30)
zum Erzeugen eines zusammengesetzten synthetischen Leistungsausgangs (10) von dem
Generator (20).
12. Erneuerbares Energiesystem (500) zum Umwandeln linearer und/oder rotierender Bewegung
eines mechanischen Geräts (510) in elektrische Energie, wobei das Gerät (500) zum
Bewirken einer relativen Bewegung zwischen einem Rotor (50) und einem Stator (60)
eines variablen Generators (20) nach Anspruch 1 zum Erzeugen eines Leistungsausgangs
(10) von dem System betreibbar ist.
13. Erneuerbares Energiesystem (500) nach Anspruch 12, wobei das mechanische Gerät wenigstens
eines umfasst: eine Gezeitenwasserturbine, eine Windturbine, eine oszillierende Windfahne,
einen Ozeanschwimmkörper, eine hydroelektrische Turbine, eine Dampfturbine.
14. Verfahren zum Erhalten eines variablen Generators (20) nach Anspruch 1, umfassenden
die Schritte:
(a) Bestimmen eines Betriebszustands von Modulen (80) des Generators (20);
(b) Ausstecken und Ersetzen eines oder mehrerer defekter Module (80), die in Schritt
(a) identifiziert wurden.
15. Verfahren zum Bereitstellen einer reagierender Ladungsstabilisation zu einem elektrischen
Verteilungsnetz, das von einem variablen Stromgenerator (20) nach Anspruch 1 verwendet
wird, wobei der Generator (20) zu dem Netz gekoppelt ist,
dadurch gekennzeichnet, dass das Verfahren umfasst:
(a) Erfassen eines oder mehrerer Parameter, die auf einen Grad elektrischer Ladung
hinweisen, welcher von dem Netz erfahren wird;
(b) Anpassen einer Wavelet- (30) Auswahl in dem Generator (20) zum Absorbieren oder
Einspeisen elektrischer Energie in das Netz, um ein Stabilisieren des Netzes gegen
Abweichungen in der Spannung und/oder Frequenz des Netzes zu unterstützen, welche
aus dem Grad der elektrischen Ladung resultiert.